package com.bitcointoolkit.common.cash;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * [类描述]
 *
 * @author caican
 */
public final class CipherUtils {
    public static final String KEY_SHA = "SHA";
    public static final String KEY_MD5 = "MD5";
    /**
     * MAC算法可选以下多种算法
     *
     * <pre>
     * HmacMD5
     * HmacSHA1
     * HmacSHA256
     * HmacSHA384
     * HmacSHA512
     * </pre>
     */
    public static final String KEY_MAC = "HmacMD5";

    /**
     * BASE64解密
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptBASE64(String key) throws Exception {
        return (new BASE64Decoder()).decodeBuffer(key);
    }

    /**
     * BASE64加密
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static String encryptBASE64(byte[] key) throws Exception {
        return (new BASE64Encoder()).encodeBuffer(key);
    }

    /**
     * MD5加密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptMD5(byte[] data) throws Exception {
        MessageDigest md5 = MessageDigest.getInstance(KEY_MD5);
        md5.update(data);
        return md5.digest();
    }

    /**
     * SHA加密
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptSHA(byte[] data) throws Exception {

        MessageDigest sha = MessageDigest.getInstance(KEY_SHA);
        sha.update(data);

        return sha.digest();

    }

    /**
     * SHA256 hash
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encryptSHA256(byte[] data) {
        try {
            MessageDigest sha = MessageDigest.getInstance("SHA-256");
            return sha.digest(data);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * for Bitcoin's 256-bit hash (double SHA-256)
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] doubleSHA256(byte[] data) {
        return encryptSHA256(encryptSHA256(data));
    }

    /** 从公钥计算 公钥hash
     * 对公钥哈希两次 SHA256 + RIPE160
     * @param data
     * @return
     */
    public static byte[] pubKeyHash160(byte[] data) {
        return RipeMDCoder.encodeRipeMD160(encryptSHA256(data));
    }


    /**
     * 初始化HMAC密钥
     *
     * @return
     * @throws Exception
     */
    public static String initMacKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_MAC);
        SecretKey secretKey = keyGenerator.generateKey();
        return encryptBASE64(secretKey.getEncoded());
    }

    /**
     * HMAC加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptHMAC(byte[] data, String key) throws Exception {
        SecretKey secretKey = new SecretKeySpec(decryptBASE64(key), KEY_MAC);
        Mac mac = Mac.getInstance(secretKey.getAlgorithm());
        mac.init(secretKey);

        return mac.doFinal(data);
    }
}
